Overview

Tool calling loops are the core execution mechanism of Agents, requiring handling various error conditions. This article introduces robust error handling architecture.

Complete Example

from typing import Any, Callable
from dataclasses import dataclass
import asyncio

class ToolError(Exception):
    pass

class ParameterError(ToolError):
    pass

@dataclass
class ToolResult:
    success: bool
    result: Any = None
    error: str = ""
    retryable: bool = False

class ToolExecutor:
    def __init__(self, max_retries: int = 3):
        self.max_retries = max_retries
    
    async def execute_with_retry(
        self,
        tool_func: Callable,
        parameters: dict
    ) -> ToolResult:
        for attempt in range(self.max_retries):
            try:
                validated_params = self._validate_params(parameters)
                if asyncio.iscoroutinefunction(tool_func):
                    result = await tool_func(**validated_params)
                else:
                    result = tool_func(**validated_params)
                return ToolResult(success=True, result=result)
            except ParameterError as e:
                return ToolResult(success=False, error=str(e), retryable=False)
            except TimeoutError:
                if attempt < self.max_retries - 1:
                    await asyncio.sleep(2 ** attempt)
        return ToolResult(success=False, error="Max retries exceeded")

Error Handling Strategy

References

• LangChain Tool Calling